1. Field of the Invention
The present invention relates to a method of identifying encoded signals, and more particularly, to a method of identifying a space-time encoded signal in a wireless communication system.
2. Discussion of the Related Art
A Broadcast Multicast Service (BCMCS) provides the ability to transmit the same information stream to multiple users simultaneously. More specifically, the BCMCS is intended to provide flexible and efficient mechanism to send common or same information to multiple users. The motivation for this service is to achieve the most efficient use of air interface and network resources when sending the same information to multiple users. The type of information transmitted can be any type of data (e.g., text, multimedia, streaming media). The BCMCS is delivered via the most efficient transmission technique based on the density of the BCMCS users, information (media type) being transmitted, and available wireless resources.
Transmission territory for each BCMCS program can be independently defined. Here, the BCMCS program refers to a logical content transmitted using the BCMCS capabilities. Moreover, the BCMCS program is composed of one or more internet protocol flows. In operation, the programs can be transmitted in time sequence on a given channel. The BCMCS programs can be transmitted to all or selected regions of the network. These regions constitute the transmission territory which refers to an area of wireless network coverage where transmission of a BCMCS program can occur. The transmission territory can be defined by a set of cells/sectors that can transmit a BCMCS program. In addition, the BCMCS programs can be received by all users or can be restricted to a subset of users via encryption.
In the BCMCS, retransmission and acknowledgement are not required since the type of transmission is “one way” and/or “one to many.”
The BCMCS subscription is normally associated with the program (e.g., ABC, TNT, ESPN), not the content (media type such as music, video, etc.). That is, by selecting the program, the user selects the type of content the user wishes to receive.
In addition, a receiver in the BCMCS over cellular networks employing a space-time coding (STC) scheme. More specifically, the STC scheme is employed to improve the reliability of data transmission in wireless communication systems using multiple transmit antennas. STCs rely on transmitting multiple, redundant copies of a data stream to the receiver in the hope that at least some of them may survive the physical path between transmission and reception in a good enough state to allow reliable decoding.
As for the receiver, it is important for the receiver to have the capability to properly and efficiently decode the received signals and determine whether or not the system is transmitting a space-time encoded signal. To this end, there may be need for the network to transmit extra information via the upper layer broadcast message indicating that space-time coding is being used. The problem with is that extra information incurs overhead. In addition, the use of space-time coding at the transmitter implies the need for a special space-time decoder with increased complexity relative to the receiver for the system without space-time coding turned on (i.e., regular transmission). However, the problem with this is that a more complex space-time decoder is needed.